The invention relates to the field of motor vehicles. More particularly, the invention relates to apparatus for providing rapid heating of portions of the engine or of its associated elements, such as the exhaust gas catalyzer. In a known electrical heater of this type, a heating element is connected in series with a bimetallic switch and a resistor. At the beginning of the heating cycle, the resistor is short-circuited and is later introduced into the circuit when the bimetallic switch has responded to the ambient temperature. It is a particular disadvantage of the known heating apparatus that high power is required even in the secondary heating period. Furthermore, the known apparatus provides no practical way to change the heating power generated during the second heating period.